The invention relates to a method and a system for a dynamically alternating radio station.
In systems utilizing a TDMA frame structure, that is time division with or without resource sharing i the space each system is divided into subsystems. Resource sharing in time and space of a common frequency band for spread out subscribers in a radio network provides a possibility for several stations to cooperate and to function simultaneously at a specific frequency band. Each radio network comprises several central stations (CS) and peripheral stations (PS) connected to and working under said central stations. Each central station and associated peripheral stations constitute a subsystem. The systems function in different embodiments in time duplex or frequency duplex with some kind of time frame structure, for instance TDMA. In different system implementations the structure is determined with regard to transmission delay and to the application information in each time frame. The capacity demand decides the number of time slots in each time frame, etc. Such systems are disclosed in PCT/89/SE/00470, PCT/SE90/00681 and PCT/SE91/526.
Said documents do not disclose any systems providing repeating radio functions, radio network branching structures, CS-CS-communication, frame synchronization, functions that will all allow the utilization of a specific frequency band by only one radio transmitter and one radio receiver. Furthermore, no method is disclosed for arranging communication and transfer information between different CS that do not terminate at common station location.
Other existing wide area radio systems functioning according to TDM/TDMA in frequency duplex in fixed applications are fox: instance SR 500 manufactured by SR Telecom, Kanada and other similar systems functioning according to a time division principle having repeating functions. Systems of this type work in TDM mode from a central station or a repeating station towards peripheral stations in a continous mode. From peripheral stations towards a central station or a repeating station the communication is handled in "bursts", i.e. time divided into time slots between peripheral stations that under each central station and repeating station shares a specific frequency that is unique in each cell or sector. In such systems a repeating station is a repeating station during all time intervals. Repeating, splitting between two radio hops is in these systems accomplished by an exchange of frequency. In such cases a double arrangement of equipment and different frequencies are required.